<template>
  <view>
    <view class="scroll-view-container">
      <!-- 左侧滑动 -->
      <!-- 左侧的滚动视图区域 -->
      <scroll-view class="left-scroll-view" scroll-y :style="{height: wh + 'px'}">
        <block v-for="(item,i) in cateList" :key="i">
          <!-- 动态样式 激活左边标记样式 -->
          <view @click="activechange(i)" :class="['left-scroll-view-item', i === active?'active':'']">{{item.cat_name}}</view>
        </block>
      </scroll-view>
      <!-- 右侧的滚动视图区域 -->
      <scroll-view :scroll-top="scrollTop" class="right-scroll-view" scroll-y :style="{height: wh + 'px'}">
       <!-- 二级分类模块 -->
        <view class="cate-lv2" v-for="(item2,i2) in cateLevel2" :key="i2">
          <view class="cate-lv2-title">/{{item2.cat_name}}/</view>
          <!-- 三级分类模块 -->
          <view class="cate-lv3-list">
            <view class="cate-lv3-item" v-for="(item3,i3) in item2.children" :key="i3"  @click="gotoGoodsList(item3)">
                <image :src="item3.cat_icon"></image>
                <text>{{item3.cat_name}}</text>
            </view>
          </view>
        </view>
      </scroll-view>
    </view>
  </view>
</template>

<script>
  export default {
    data() {
      return {
        wh:0,//当前设备可用高度
        cateList:[],
        active:0,
        cateLevel2:[],
        scrollTop:0,
      };
    },
    onLoad(){
     const sysinfo= uni.getSystemInfoSync()
      console.log(sysinfo)
      this.wh= sysinfo.windowHeight
      this.getCateList()
    },
    methods: {
      gotoGoodsList(item){
       uni.navigateTo({
         url:'/subpkg/goods_list/goods_list?cid=' +item.cat_id
       }) 
      },
      async getCateList() {
      const {data:res}=await  uni.$http.get('/api/public/v1/categories')
        if(res.meta.status!==200) return uni.$showMsg()
        this.cateList=res.message
        // 二级分类赋值
        this.cateLevel2=res.message[0].children
      },
      // 拿到索引i
      activechange(i){
        this.active = i
        // 重新为二级分类赋值
        this.cateLevel2=this.cateList[i].children
        this.scrollTop = this.scrollTop === 0 ? 1 : 0
      }
      
    },
  }
</script>

<style lang="scss">
  .cate-lv3-list{
    display: flex;
    flex-wrap: wrap; //换行
    .cate-lv3-item{
      width: 33.33%;
      display: flex;
      flex-direction: column;
      justify-content: center;
      align-items: center;
      margin-bottom: 10px;
      image{
        width: 60px;
        height: 60px;
      }
      text{
        font-size: 12px;
      }
    }
  }
  
  .cate-lv2-title{
    font-size: 12px;
    font-weight: bold;
    text-align: center;
    padding: 15px 0;
  }
.scroll-view-container{
  display: flex;
  .left-scroll-view{
    width:120px;
    .left-scroll-view-item{
      background-color: #F7F7F7;
      line-height:60px;
      text-align: center;
      font-size: 12px;
      // 激活项
      &.active{
        background-color: #fff;
        position: relative;
        // 微元素 渲染矩形的标记
        &::before{
          content: '';
          display: block;
          width: 3px;
          height: 30px;
          background-color: red;
          position: absolute;
          top: 50%;
          left: 0;
          transform: translateY(-50%);
        }
      }
    }
  }
}
</style>
